<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>flex三栏布局</title>
    <style>
        body{
            display: flex;
        }
        .left{
            width:150px;
            height:150px;
            background-color: deeppink;
        }
        .right{
            width:150px;
            height:150px;
            background-color: wheat;
        }
        .main{
            width:100%;
            height:150px;
            background-color: green;
        }
    </style>
</head>
<body>
<div class="left"></div>
<div class="main"></div>
<div class="right"></div>
</body>
</html>